In recent years, virtual reality and augmented reality techniques have entered the stage of high speed development, and the head-mounted displays that are applied to them also become hot spot products of the field of displaying in recent years. Head-mounted displays are required to have compact structures and small weight to be convenient for head wearing. Additionally, the angle of view is required to be as large as possible, to increase the observation range. Furthermore, the image quality should be emphatically considered, by controlling types of aberrations of optical imaging systems. Therefore, eyepiece optical systems are the core of head-mounted displays.
The patent with the patent number “CN104823079A” provides a Fresnel lens and an optical device. The refraction type Fresnel lens can reduce the noise that is created by the reflection and/or refraction of light on the sidewall, to improve the imaging quality. However, the wide angle characteristic of the refraction type Fresnel lens can still be further optimized, to satisfy the demand of the market, especially the higher requirements on optical imaging systems by head mounted displays.